From the Guidelines
Hemolytic Uremic Syndrome (HUS) is a disorder characterized by a form of thrombotic microangiopathy with renal failure, hemolytic anemia, and severe thrombocytopenia, as defined by the American Society of Clinical Oncology clinical practice guideline 1.
Definition and Signs
The condition is marked by a range of signs and symptoms, including:
- Bloody diarrhea
- Decreased urination or blood in the urine
- Abdominal pain, vomiting, and occasionally fever
- Pallor
- Small, unexplained bruises or bleeding from the nose and mouth
- Fatigue and irritability
- Confusion or seizures
- High blood pressure
- Swelling of the face, hands, feet, or entire body
Clinical Presentation
HUS typically presents with a combination of these symptoms, which can vary in severity. The diagnosis of HUS is critical, as prompt recognition and management are essential for improving outcomes. According to the guideline 1, the condition can be triggered by various factors, including immune-related adverse events in patients treated with immune checkpoint inhibitor therapy.
Management
While the provided evidence does not directly address the management of HUS, it is crucial to prioritize supportive care, including fluid and electrolyte management, blood pressure control, and renal support. In severe cases, dialysis may be necessary, and blood product transfusions may be required to manage anemia and bleeding complications. It is essential to monitor patients closely for complications, such as neurological symptoms, cardiac involvement, and pancreatic insufficiency, and to provide long-term follow-up due to the risk of chronic kidney disease.
From the Research
Definition and Characteristics of Hemolytic Uremic Syndrome (HUS)
- HUS is defined by the simultaneous occurrence of nonimmune haemolytic anaemia, thrombocytopenia, and acute renal failure 2
- It leads to the pathological lesion termed thrombotic microangiopathy, which mainly affects the kidney, as well as other organs 2
- HUS is associated with endothelial cell injury and platelet activation, although the underlying cause may differ 2
Causes and Types of HUS
- Most cases of HUS are associated with gastrointestinal infection with Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) strains 2
- Atypical HUS (aHUS) is associated with complement dysregulation due to mutations or autoantibodies 2
- Other forms of HUS include those triggered by neuraminidase-producing Streptococcus pneumoniae (pneumococcal-HUS) 3
- HUS can also be classified as typical or atypical, with atypical HUS having a diverse etiology, including inherited or acquired abnormalities that lead to a failure to control complement activation 4
Clinical Features and Diagnosis
- Hemolytic anemia with schistocytes, thrombocytopenia without evidence of disseminated intravascular coagulation, and renal failure are consistently found in HUS patients 5
- A prodromal diarrhea, with blood in the stools, is observed in typical HUS, related to pathogenic enterobacteria, most frequently E. Coli O157:H7 5
- Early identification and initiation of best supportive care, with microbiological input to identify the pathogen, result in a favorable outcome in most patients 4
Treatment and Management
- Plasma therapies can reverse defective complement control, and it is now possible to specifically target complement activation 4
- Complement inhibition by eculizumab administration leads to a rapid and sustained normalization of hematological parameters with improvement in long-term renal function in patients with aHUS 3
- Supportive care, including plasma infusions and plasma exchanges, is effective in most cases to treat hemolysis and thrombocytopenia 5